1987 Mercury Grand Marquis Engine Swap

[87MercMan]

Hey guys,

I have a 1987 Mercury Grand Marquis. It has the 302 5.0L EFI engine, it's stock engine.

1.) What is the largest most powerful engine that will fit in this car without too many heavy modifications?

2.) What is the maximum horsepower/torque than can be realized in this stock 302 engine?

3.) How much power will the original stock automatic 4 speed with O.D. transmission handle?



Thanks guys. As you can tell I'm trying to get all the ponies under the hood of this merc boat as I can. But I need your help, what engine should I use? I would like to see something around 500 horsepower, however I realize that with the 302 at least, perhaps 400 horsepower is a more realistic goal. Tips or pointers? Let's hear 'em!

[fearsomefairmont]

Hi there,
If you really want to make that Grand Marquis go, you need to massive cubes to do so. I have an 1983 Lincoln Towncar, similar in size and engine, and a 302 is just not enough engine to get a 4500 lb+ car to go. The easiest route is probably a 351 windsor, which would fit relatively easily in the large engine compartment. I would also skip fuel injection and go with a carb of some type. Another way to get more power would be to stroke the windsor out to 408 cubes, or if you really want to do it right, get a 460 from a truck of late 1970's lincoln and drop that in. No, the stock tranny wouldn't work and the engine mounts would require modification, but a 460 can be stroked to 600+ cubes and make over 700 hp set up properly. Just remember, you are dealing with a huge car and it is just tough to make alot of mass go quick. My 1978 fairmont can accomodate the same motors as your car, but is two doors and weighs roughly half of what the Grand Marq does. Anyways, good luck and fire away. I still think it would be really cool though, even if it wouldn't be that fast. A mild 460 should make around 400 hp which would probably get the car into the low 13's or high 12's.

[fearsomefairmont]

About the AOD tranny in that car, it will take about 250 hp max and if there is any sort of serious torque or a high stall converter then it will go up in smoke quickly. The only way to go is a race prepped C4 or a C6 (heavy duty truck tranny). With a mildly warmed over stock 302, you would be lucky to see 300 hp. It also depends on the exact 302, as the 302 HO is considerably easier to build up further without serious modifications. I believe only cop cars and mustang gt's received these motors however. Here is the quintessential question - "Speed costs money, son. How fast do you want to go?"

[anarkist61]

It's gonna cost but you could drop in a Mustang GT engine (will need to reroute linkages) with a simple aftermarket Supercharger. Add duals and a built AOD and it should be reliable enough once you get the bugs worked out. Going this route (with dual cats) should also allow it to still pass any emissions testing you may or may not have. Keep it simple and it'll have less headaches.

[FordInPossession]

Why would anyone go from an Overdrive transmission to a C-4 or C-6? That makes no sense what-so-ever because you'll lose all of your high speed cruising. An experienced Transmission shop can build that AOD to withstand 400-500 HP. It'll cost a pretty penny, but it can be done. As for as upping the cubes to gain power.... look at all the bolt on parts for the 5.0L V8's and look at all the engine kits available too. No need to go to a 351 (No real difference between that and a 302 power wise) Keep it cheap, I have a 306 in my Torino GT and it moves teh car just fine.

[Samurai0]

Originally Posted by FordInPossession

Why would anyone go from an Overdrive transmission to a C-4 or C-6? That makes no sense what-so-ever because you'll lose all of your high speed cruising. An experienced Transmission shop can build that AOD to withstand 400-500 HP. It'll cost a pretty penny, but it can be done. As for as upping the cubes to gain power.... look at all the bolt on parts for the 5.0L V8's and look at all the engine kits available too. No need to go to a 351 (No real difference between that and a 302 power wise) Keep it cheap, I have a 306 in my Torino GT and it moves teh car just fine.

Dude, Where do you come with these replies?
Do you even understand what an AOD tranny offers?

Even if they exchange the stock torque converter for a 3300rpm high-stall converter to handle the increased horsepower, and change out the transmission gasket kit for a performance kit, you'll never get the performance that a Rachet shifter could offer.

The C-4 or C-6 is the viable solution for adding a shifter. They were available in the older Merc's to handle the 400hp engines.

Extra CID's will always make a difference. Although the 302CID engine can rev-out more than the 351CID engine.

Don't assume everybody just want's to cruise around. These performance upgrades are for 'performance' not economy.

Later

[fredjacksonsan]

I heard there is a drag racer out there somewhere that can rebuild the A4OD to handle the kind of power you're talking about for 2 or 3K, but so far that is just a rumor in the wind.